1. Field of the Invention
The present invention relates to an optical disk drive, and in particular to a flexible printed circuit that is more effective in discharging static charges that may be experienced by the optical disk drive.
2. Description of the Prior Art
Optical disk drives are becoming more popular in the market, and the optical disk drives are considered as standard equipment on personal computers for several years. Recently, slim-type optical disk drives are usually shipped with portable computer such as notebook, and the users can conveniently load and unload optical disks via the slim-type optical disk drives. In attempt to reduce the cost and adapt to the limited space constraint within notebooks, the conventional motor for disk loading and unloading operation has been eliminated. FIGS. 1-2 illustrate the conventional slim-type optical disk drive and its components. The conventional slim-type optical disk drive has a chassis 1, a disk tray 2, a playback unit 3, a front bezel 4 and a flexible printed circuit 5. The disk tray 2 and the playback unit 3 are positioned inside the chassis 1, and the playback unit 3 is positioned above the disk tray 2. When the user pushes an ejection button 41 defined in the front bezel 4, the disk tray 2 is ejected along the direction of arrow A as shown in FIGS. 1 and 2. Then, the user can place an optical disk on the playback unit 3 and then push the disk tray 2 back into the chassis 1 along the reverse direction of arrow A.
Referring to FIG. 2, the flexible printed circuit 5 has a first portion 51 and a second portion 52. A first connecting end 53 is integrally formed with the first portion 51, and a second connecting end 54 is integrally formed with the second portion 52. As shown in FIG. 2, the first connecting end 53 of the flexible printed circuit 5 can be electrically connected with the disk tray 2, and the second connecting end 54 can be electrically connected with the chassis 1. Besides, the second portion 52 of the flexible printed circuit 5 is attached to the chassis 1 by an adhesive layer 66 (as shown in FIG. 4). For simplicity, the first connecting end 53 is not connected with the disk tray 2.
FIG. 3 illustrates a plan view of the flexible printed circuit 5 in the prior art. As shown in FIG. 3, the flexible printed circuit 5 is generally U-shaped and has a plurality of separate electrical wires. The electrical wires are substantially parallel and are used to achieve electrical connection between the chassis 1 and the disk tray 2. As describe above, the first connecting end 53 of the flexible printed circuit 5 is electrically connected to the disk tray 2, and the second connecting end 54 of the flexible printed circuit 5 is electrically connected to the chassis 1.
FIG. 4 is a cross section of the flexible printed circuit 5 taken along line B-B of FIG. 3 and illustrates the combination of several layers. Referring to FIG. 4, the flexible printed circuit 5 has a multi-layers structure and includes a cover layer 61, a copper foil 63 and a base layer 65, and the flexible printed circuit 5 also has adhesive layers 62 and 64. Besides, the cover layer 61 and the base layer 65 are made of dielectric material (e.g. polyimide), and adhesive layers 62 and 64 are not electrically conductive. By the way, a finished single-layer structure bought from market usually consists of a copper foil 63, an adhesive layer 64 and a base layer 65. It is necessary for a single-layer structure to be a multi-layers structure by processing.
The second portion 52 of the flexible printed circuit 5 can be attached to the chassis 1 of the optical disk drive by the adhesive layers 66. When the user touches the optical disk drive, most of static charges usually flow to the optical disk drive and some of static charges may accumulate in the optical disk drive. As shown in FIG. 2, static charges can be discharged through an IDE bus 7 of the optical disk drive, and otherwise, excess electric charges flows through the chassis 1 and the disk tray 2, some components (e.g. optical pickup head) may be damaged, thereby rendering the optical disk drive unusable.
Thus, there is need to development for a flexible printed circuit for use in an optical disk device, and the flexible printed circuit is more effective in discharging static charges that may be experienced by the optical disk drive.